Carrier current receiver



Jfl 1941- A. ARZMAIER 2,229,433

' CARRIER CURRENT RECEIVER Filed July 13, 1937 BY )IQM ATTORN EYPatented 21, 1941 PATENT OFFICE CARRIER CURRENT RECEIVER ApplicationJuly 13, 1931, Serial No. 153,369

I In Germany July 1c, 1938 a 5 Claims.

This invention relates to a receiver amplifier for telegraphy withcanier current in which magnetic amplifiers are utilized.

It has beenproposed in the prior art to use 5 magnetic amplifiers asreceiving arrangements for the carrier current telegraphy. However, inthis case, the signals can be transmitted only as single currentsignals. In accordance with the present invention an improvement in sucharrangements is obtained in that the circuit through which the amplifiedcurrent of the magnetic amplifier passes, has superimposed thereon aiurtherdirect current such that it'iurnishes output signals of increasedamplitude than those obtained by the single cm'rent signals produced bythe amp ifi ra v To operates magnetic modulator, a local alternatingcurrent source is required. In accordance with a further feature of theinvention,'the go current is also derived irom this alternating currentsource 'which is to be superposed on. the amplified current afterrectification. This afiords theadvantage that at variations of thislocal alternating current source,' the amplified as well as as thesuperimposed current vary in an identical manner thereby avoidingdistortions. Fig. 1- shows a schematic wiring diagram of a. circuitarrangement, while Fig. 2a to indicate the current pattern in'tfie 30output circuit of the amplifier, and

Fig". 3 shows. the circuit anfangement with the details 01 the magneticamplifier.

Referring now in detail tom. l. of the drawing, the incoming telegraphsignals are applied 88 to the terminals A and B in the. form 0!chopped-alternating current. signals. They are I detected in therectifier Gil and impressed upon the magnetic-amplifier MV as' directcurrent signals, the specific "circuit of which will be ex-- o plainedmore in detail in connection with Fig, 3.

At the terminals-C, D, the local alternating current source is connectedkeyed'in the magnetic amplifier IV by the ,direct current signalsarriving across the detector Gii.-" In-the recti- 45 her Gii the keyedalternating current signals of the local'alternatin'g'current source aredetected by the irequency 1|..as eaplainedin the German patent mentionedabove, and applied to the cutput circuit of the lmplifier.' Inaccordancewith so theinvention, a part or the alternating current oi'the local current "source is immediately branched oil at the terminalsC,-D and likewise perposed on the output circuit'oi the amplifieracrossthe detector Git. A as through the telegraph recording apparatuscon.

. sidered as a; chopped or hashed alternating curoi iourtchokes. Eachntwiilthuspass.

said current being direct currents produced in nected with the terminalsE, F, composed of the two the detectors. The valuesoi the currents aresuitably chosen according to the relationship shown in Fig. 2. g whichshows substantially a 1 tot2 ratio, so that the current passing throughthe detector on is onewhali as large as the current derived from themagnetic amplifier across the detector Gi2. During the signal'pause, a.current will then pass 10 in the output circuit across the terminals E,P such as represented by the line i, 2, i, Q; However, as soon asslgnalshaving twice the amplitude and the reversed sign. arrive across.the, magnetic amplifier; a pattern according to the line i, 2, t, 4,1, 6will be obtained. The shape of the signals, according to Fig. 2,resultsirom the fact that in Fig. 3 alternating current signals are iedto terminals A\and B. Theyare to be con-' renttrain. After rectificationby rectifier Gii theyv constitute the one half wave or said alternatingcurrent train, the envelope curve 01' which is determined by the signalsoithe amplitude a. Thus, there appears inthe output circuit of theamplifier a current of increased'amplitude which is of particularadvantage to certain types oi telegraphic operation, a 0

I In Fig. 3, the currents rcetified by the rectifier Gil are supplied tothe magnetic amplifier windso ings at, M, ci, di 0! a bridge circuitconsisting oi these chokeshas three windings. Across one of the othertwo windings, thelocal carrier current is supplied for whichthe magneticamplifier is normally maintained in equilibrium for the state of rest orno signal response. Across the third winding a;local direct current iswhich takes care of the preliminary magnetizing oi the magnetic; ampli-,'fier, so that the working point of the amplifier 0 can bejset to itsmost favorable value by means oi the preliminary magnetizing. when atelegraph signal arrives across the windings ai, bi, ci, di 0! themagnetic amplifier, the equilibrium oi the bridge (not shown) tor-thelocal carrier current and indicated at terminalsdisturbedsothatacrossthepointslflunalternatingcurrentbeains'tofiowwhichwillbede tected by the detectorGI, Land applied to the output circuit. mm the tollgwing it will belowso" explained how rectifier GI: of Fig. 3 opera s Rectifier Gig isparallel to the local input terl minals C, D. As the local alternatingcurren oif'irequency F1 is permanently applied to terminals C, D, therewill be permanently present at.

the output terminals of rectifier Gila, a direct potential of a certainmagnitude absolutely independent of whether signals are received at A, Bor not. If now a weak alternating current is re- 5 ceived and applied toinput terminals A, B, rectifier Glz will furnish a direct potential ofcertain magnitude. The direct potentials furnished by rectifier G13 andGlz will have a certain ratio in regard to one another, that is, thepotential at Gla is related to the potential at Glz as an 1 to 2 ratio.The potentials furnished by rectifier Gia and Glz are connected inseries, however, not so that the single potentials furnished by therectifiers add up, but oppositely so that a. current ,of increasedamplitude develops at the output terminals E, F. This 'is done in thefollowing manner: a

It is assumed that rectifier Gla is arranged to be able to furnish apotential of two volts. Ac-

cording to the'above 1 to 2 ratio, rectifier Giz furnishes double thepotential of rectifier Gia,

that is, in the present example a potential of four volts. If nopotential is applied to terminals A, B, .then at theoutput terminals E,F, a potential of two volts derived from rectifier Gis will exist, forinstance, at terminal E and at terminal F. When signals are received atthe input terminals A, B, rectifier Giz furnishes a potential of fourvolts but of opposite direction from rectifier Gls, that is, atterminals E, F a potential of +2 volts (derived from rectifier Gla) and-4 volts (derived from rectifier Giz) exists. Thus, at the outputterminals E, F a potential of 24=2 volts exists; however, so that nowthe minus pole is at terminal E and the plus pole is at terminal F. Thedevelopment of the increased current at the output terminals E, F whichwas explained above it will now be seen by referring to Fig. 2, thatrectifier GI: furnishes, 40 independent of whether or not an alternatingcurrent is applied to terminals A, B, a direct potential of an amplitudea, that is, at the output terminals E, F, there is applied a currentrepresented by points i, 2, 5, B. When signals are 45 received at A, B,rectifier Giz furnishes double the potential of rectifier Gia of anamplitude 1). Thus, at the instant the signals begin to occur, thecurrent drops from point 2 to point 3, and as the potential is preservedat the output termi- 50 nals E, F until the signal received at A, B isterminated, the current proceeds from point 3 to point A of Fig. 2. Atthe instant of termination of signal, that is, at the instant where nopotential exists at terminals A, B, also the potential 5 furnished byrectifier (312 is lacking and now again the potential from Gla is aloneeflective so that point l drops to point 5. Till the indicated beginningof the signal, the current proceeds again above the time line F. As, inthe 0 Fig. 1, a direct current is branched ofl from the local carriercurrent, and conducted across the detector GI, 3, said direct currentbeing superimposed on the direct current keyed in the output circuit.

aaaaaee What is claimed is:

i. A circuit arrangement for the amplification of incoming alternatingcurrent telegraph signals comprising a magnetic amplifier having aninput and an output circuit, a first rectifier connected to the input ofsaid magnetic amplifier for rectifying the incoming alternating currenttelegraph signals, a second rectifier. connected to the output of saidmagnetic amplifier, and a third rectifier connected to a source of localalternating currents and combined with the outputs of said magneticamplifier and said second rectifier so that a direct current will appearin the output circuit, the direct current having an increased amplitudeover that obtained by the outputs of said first and second rectifiers.

2. A circuit arrangement according to claim 1 characterized in that aportion of the source of said local alternating current is connected tothe magnetic amplifier and branched off after rectification so as to becontinuously superimposed on the direct current output circuit of saidmag-- .netic amplifier.

-3. A circuit arrangement according to claim 1 characterized in that thevalue of direct current which is supplied by said source of localalternating currents and connected to the output circuit of the magneticamplifier is half as large and of an opposite direction as comparedwiththe direct current from the output of said first rectlfier.

4. A circuit arrangement for the amplification of incoming alternatingcurrent telegraph signals comprising a magnetic amplifier having aninput and an output circuit, said magnetic amplifier having four chokecoils each having three windings, said coils arranged as a bridge whichis balanced for a source of local alternating current, a first rectifierconnected to the input of said magnetic amplifier for rectifying theincoming alternating current telegraph signals, a second rectifierconnected to the output of said magnetic amplifier, and a thirdrectifier connected to said source of local-alternating currents, thebalance oi said bridge being upset by telegraph signals rectified bysaid first rectifier such that the amplified current in the outputcircuit is of a greater amplitude than'that obtained by the outputs ofsaid first and second rectifiers.

,5. A receiver amplifier circuit for carrier current receivers withmeans to avoid distortions due to variations of local input currents andthe superimposed signals comprising a magnetic amplifier having an inputand an output circuit, a first rectifier connected to the input of saidmagnetic amplifier tor rectifying the incoming alternating currentsignals, a second rectifier. connected to the output of said magneticamplifier, and a third rectifier connected to a source of localalternatlng currents, the outputs of said second and third rectifiersconnected in series to form an output circuit so theslgnal potentialsadd to give an increased amplitude over that obtained by the outputs ofthe first and second rectifiers;

ALFONS ARZMAIER.

